1. Field of the Invention
The present invention relates to an aircraft steering angle control system that turns an airframe that is taxiing to a desired direction using an operation signal related to a steering angle as a control command signal for a nose steering wheel, and particularly relates to an aircraft steering angle control system that minimizes the amount of skidding of the airframe that is turning on a low-μ taxiway surface such as an icy taxiway surface and allows for directional control of the airframe by a steering command.
2. Description of the Related Art
In an aircraft steering angle control system that controls a nose wheel using an electric signal, a steering command signal via a steering wheel, a pedal, or the like is used as a control command for a nose steering wheel, and an airframe is turned to a desired direction by changing the angle of the nose steering wheel.
FIG. 6 is an explanatory diagram showing a correlation between a steering command, the angle of a nose steering wheel, and a rate of turn of a conventional steering angle control system (see Japanese Unexamined Patent Application, Publication No. 8-133189, for example). Steering commands correspond directly to angles of the nose steering wheel, and as the pilot increases the steering command, the angle of the nose steering wheel also increases. Accordingly, the rate of turn of the airframe increases as well. However, if the aircraft skids while it is turning, the rate of turn decreases even though the command increases, so that the airframe can no longer be steered to the desired direction, and in the worst case, the airframe falls into a so-called out-of-control state (unmaneuverable state). For this reason, incidents during movement on an icy taxiway surface, such as deviation of the airframe from a taxiway or contact with an obstruction due to loss of directional control by a steering command, have occurred frequently.